1. Field of the Invention
The present invention relates to a method and apparatus for processing information, a storage medium and a software program and, more particularly, to a method and apparatus for processing information, a storage medium and a software program for assuring movement transparency at an upper layer without modifying an existing protocol.
2. Description of the Related Art
As mobile computers become ubiquitous, users frequently carry computers with them. The user not only carries a mobile computer, but also connects the computer to a network at a destination of the user to receive a variety of services through the network.
In today's mobile computing environment, a node, i.e., a device (a computer) to receive service through a network, is required to be mobile. Such a node, if moved in the location thereof, must continuously remain communicable.
Based on the IP V6 (Internet Protocol Version 6), Mobile IP V6 has been proposed as a protocol to assure movement transparency at the network layer by IETF (the Internet Engineering Task Force). Japanese Patent Application No. 2000-000560, assigned to the assignee of this invention, also discloses a technique (hereinafter referred to as VIP V6) based on the IP V6.
In accordance with the technique disclosed in Japanese Patent Application No. 2000-000560, the least significant 64 bits of an IP V6 address are set to be unique to assure movement transparency at the IP layer.
Movement transparency cannot be assured in a session at an IPsec (Security Architecture for Internet Protocol) layer or an upper layer (TCP/UDP (User Datagram Protocol)) without modification in an existing protocol.
A technique is contemplated to assign a predetermine fixed value to a network prefix, which is the most significant 64 bits of the IP V6 address. In this case, however, standardization is must be achieved to use a particular fixed network prefix to the VIP V6 protocol in accordance with the foregoing Patent Application No. 2000-000560.
Upon receiving a packet, a receiver node needs to determine whether to perform a session at the Ipsec layer or the upper layer (TCP/UDP) or an ordinary session using a source address contained in the received packet. To this end, the receiver node describes an ID (Identification) identifying a node in the least significant 64 bits of the IP V6 address, or indicates a “fixed value+node identification ID” to a domain name server to check whether the address is registered.
In this arrangement, however, at least one network prefix is dedicated to a session at the Ipsec layer or the upper layer. The address is thus consumed in vain.